In firefigther's garments and the like the use of multiple material layers can restrict movement causing difficulty for the wearer and increasing stress.
The human body redistributes itself during motion, such as during the flexing of extremity joints. During this movement, there is normally tension over one area of the material for every distension at another area of the material, in an extremity portion of the garment. For instance, the front of the unflexed human leg or the back of the unflexed human arm (particularly in the joint area) is significantly less tensed than the same body portion measured at full flex. This means unless clothing has sufficient excess in it to allow this "growth" during motion; it binds and restricts in fully flexed body portion. This is especially troubling in firefighting, since when the clothing is brought in tight contact to the body, insulation is reduced (as insulating air is forced out of the system). A garment pressed tightly against the firefigther's body presents a much more efficient pathway for burning injury to approach his body.
It would not be a solution simply to make the extremity portions of the garment oversized throughout so as to maintain an accommodating fit even when the wearers extremities are in a nonflexed positions. This would result in the firefigther being unable to work comfortably and efficiently due to the additional bulk and loose fit. Also, the cost of additional material would substantially increase the cost of the garment.
Various approaches have been made to resolve this problem. Examples of such approaches are described in U.S. Pat. No. 5,031,242 to Aldridge et al. and U.S. Pat. No. 5,072,454 to Trahan, both of which are hereby incorporated herein by reference. These patents teach providing the extremity portion of the garment with an aperture at the joint position, and covering this aperture with a cover piece of material adapted to provide additional space within the extremity portion at the joint position. The apertures and corresponding covering pieces used in the prior art can generally be described as rectangular or truncated elliptical in shape and generally symmetrical about the lateral axis passing through the "flex point" of the extremity, used herein to mean the point at which the elbow or knee bends. These constructions have the disadvantage of providing a geometry which is not precisely suited to the movement of a jointed body part; particularly about the flex point making such a construction unnecessarily expensive to produce. Also, although some of the cover pieces may be constructed of multiple pieces to make their final shape, these cover pieces generally collapse from their extended position (i.e. when the joint is flexed) once the extremity is straightened, leaving less space between the outer layer of the garment and the inner layer(s), space which can add desirable insulative value to these portions of the garment. Expansion areas which collapse upon straightening of the extremity must of course be re-extended upon each flex of the extremity joint, increasing the work load on the extremity.
In view of some of the shortcomings of the prior art, it is an object of the present invention to provide an extremity portion of a multi-layered protective garment, such as that used by a firefigther, which allows comfortable and unencumbered movement of the extremities while minimizing the cost of materials and manufacturing as compared to some other prior art constructions.
It is also an object of one embodiment to provide such an extremity portion of a multi-layered protective garment which allows for additional insulative space at the joint areas throughout the movement range of the extremity, and which aids in maintaining such space once extended, making subsequent joint flexion less stressful.
It is also an object of one embodiment of the present invention to produce a firefigther's garment which will comply with governing NFPA standards.
It should be understood that while some of the advantages of the protective garment of the present invention are described in terms of a firefigther's garment, the protective garment of the present invention is not limited to use in firefighting. Rather, it may be used for protection against similarly hostile environments.
The present invention represents an improvement over constructions of the prior art by achieving such objects and providing advantages flowing therefrom. Additional advantages, and the solutions to other problems in the prior art, may become apparent to one of ordinary skill in the art in light of the disclosure of the present invention, its manufacture and its use.